// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.
// All rights reserved. This file is part of cc-backend.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package memorystore

import (
	"math"

	"github.com/ClusterCockpit/cc-lib/schema"
	"github.com/ClusterCockpit/cc-lib/util"
)

type APIMetricData struct {
	Error      *string           `json:"error,omitempty"`
	Data       schema.FloatArray `json:"data,omitempty"`
	From       int64             `json:"from"`
	To         int64             `json:"to"`
	Resolution int64             `json:"resolution"`
	Avg        schema.Float      `json:"avg"`
	Min        schema.Float      `json:"min"`
	Max        schema.Float      `json:"max"`
}

type APIQueryRequest struct {
	Cluster     string     `json:"cluster"`
	Queries     []APIQuery `json:"queries"`
	ForAllNodes []string   `json:"for-all-nodes"`
	From        int64      `json:"from"`
	To          int64      `json:"to"`
	WithStats   bool       `json:"with-stats"`
	WithData    bool       `json:"with-data"`
	WithPadding bool       `json:"with-padding"`
}

type APIQueryResponse struct {
	Queries []APIQuery        `json:"queries,omitempty"`
	Results [][]APIMetricData `json:"results"`
}

type APIQuery struct {
	Type        *string      `json:"type,omitempty"`
	SubType     *string      `json:"subtype,omitempty"`
	Metric      string       `json:"metric"`
	Hostname    string       `json:"host"`
	Resolution  int64        `json:"resolution"`
	TypeIds     []string     `json:"type-ids,omitempty"`
	SubTypeIds  []string     `json:"subtype-ids,omitempty"`
	ScaleFactor schema.Float `json:"scale-by,omitempty"`
	Aggregate   bool         `json:"aggreg"`
}

// TODO: Optimize this, just like the stats endpoint!
func (data *APIMetricData) AddStats() {
	n := 0
	sum, min, max := 0.0, math.MaxFloat64, -math.MaxFloat64
	for _, x := range data.Data {
		if x.IsNaN() {
			continue
		}

		n += 1
		sum += float64(x)
		min = math.Min(min, float64(x))
		max = math.Max(max, float64(x))
	}

	if n > 0 {
		avg := sum / float64(n)
		data.Avg = schema.Float(avg)
		data.Min = schema.Float(min)
		data.Max = schema.Float(max)
	} else {
		data.Avg, data.Min, data.Max = schema.NaN, schema.NaN, schema.NaN
	}
}

func (data *APIMetricData) ScaleBy(f schema.Float) {
	if f == 0 || f == 1 {
		return
	}

	data.Avg *= f
	data.Min *= f
	data.Max *= f
	for i := 0; i < len(data.Data); i++ {
		data.Data[i] *= f
	}
}

func (data *APIMetricData) PadDataWithNull(ms *MemoryStore, from, to int64, metric string) {
	minfo, ok := ms.Metrics[metric]
	if !ok {
		return
	}

	if (data.From / minfo.Frequency) > (from / minfo.Frequency) {
		padfront := int((data.From / minfo.Frequency) - (from / minfo.Frequency))
		ndata := make([]schema.Float, 0, padfront+len(data.Data))
		for range padfront {
			ndata = append(ndata, schema.NaN)
		}
		for j := 0; j < len(data.Data); j++ {
			ndata = append(ndata, data.Data[j])
		}
		data.Data = ndata
	}
}

func FetchData(req APIQueryRequest) (*APIQueryResponse, error) {
	req.WithData = true
	req.WithData = true
	req.WithData = true

	ms := GetMemoryStore()

	response := APIQueryResponse{
		Results: make([][]APIMetricData, 0, len(req.Queries)),
	}
	if req.ForAllNodes != nil {
		nodes := ms.ListChildren([]string{req.Cluster})
		for _, node := range nodes {
			for _, metric := range req.ForAllNodes {
				q := APIQuery{
					Metric:   metric,
					Hostname: node,
				}
				req.Queries = append(req.Queries, q)
				response.Queries = append(response.Queries, q)
			}
		}
	}

	for _, query := range req.Queries {
		sels := make([]util.Selector, 0, 1)
		if query.Aggregate || query.Type == nil {
			sel := util.Selector{{String: req.Cluster}, {String: query.Hostname}}
			if query.Type != nil {
				if len(query.TypeIds) == 1 {
					sel = append(sel, util.SelectorElement{String: *query.Type + query.TypeIds[0]})
				} else {
					ids := make([]string, len(query.TypeIds))
					for i, id := range query.TypeIds {
						ids[i] = *query.Type + id
					}
					sel = append(sel, util.SelectorElement{Group: ids})
				}

				if query.SubType != nil {
					if len(query.SubTypeIds) == 1 {
						sel = append(sel, util.SelectorElement{String: *query.SubType + query.SubTypeIds[0]})
					} else {
						ids := make([]string, len(query.SubTypeIds))
						for i, id := range query.SubTypeIds {
							ids[i] = *query.SubType + id
						}
						sel = append(sel, util.SelectorElement{Group: ids})
					}
				}
			}
			sels = append(sels, sel)
		} else {
			for _, typeID := range query.TypeIds {
				if query.SubType != nil {
					for _, subTypeID := range query.SubTypeIds {
						sels = append(sels, util.Selector{
							{String: req.Cluster},
							{String: query.Hostname},
							{String: *query.Type + typeID},
							{String: *query.SubType + subTypeID},
						})
					}
				} else {
					sels = append(sels, util.Selector{
						{String: req.Cluster},
						{String: query.Hostname},
						{String: *query.Type + typeID},
					})
				}
			}
		}

		// log.Printf("query: %#v\n", query)
		// log.Printf("sels: %#v\n", sels)
		var err error
		res := make([]APIMetricData, 0, len(sels))
		for _, sel := range sels {
			data := APIMetricData{}

			data.Data, data.From, data.To, data.Resolution, err = ms.Read(sel, query.Metric, req.From, req.To, query.Resolution)
			if err != nil {
				msg := err.Error()
				data.Error = &msg
				res = append(res, data)
				continue
			}

			if req.WithStats {
				data.AddStats()
			}
			if query.ScaleFactor != 0 {
				data.ScaleBy(query.ScaleFactor)
			}
			if req.WithPadding {
				data.PadDataWithNull(ms, req.From, req.To, query.Metric)
			}
			if !req.WithData {
				data.Data = nil
			}
			res = append(res, data)
		}
		response.Results = append(response.Results, res)
	}

	return &response, nil
}